Solvent refining of mineral oil



' I This invention relates to refining rafilnate phases, respectively, rich in low viscosity index and high viscosity index constituents of the oily, These phases are then removed and the UNITED-STATES PATENT OFFICE SOLVENT REFINING F MnvERAL OIL Louis A. Clarke, Fishkill, and Edwin C. Knowles,

Beacon,

N. Y., assignors to The Texas Company, New York, N. IL, a corporation of Delaware No Drawing. Application October 9, 1935,

Serial No. 44,254

6 Claims.

mineral oil andmore particularly to refining of mineral oil by solvent extraction.

, The invention broadly contemplates a process 8 for' extracting mineral 'oil with an extraction .solvent in the presence of an added material, whereby the extraction solvent is rendered more effective as regards the removal of certain un- '.;;l; desired constituents from the oil undergoing 10 treatment. I

pt lMore specifically, the invention comprises extraeting mineral lubricating oil containing solid 1 and semi-solid asphaltic constituents, and par- ,tlcularly a residual type of oil, withaselective solvent in the presence of an added material having a relatively high ionization constant and "gada'pted to increase the solvent action of the ex- Jtraction solvent upon the asphaltic constituents of the oil.

,The added material may comprise a small amount'jofeither an organic or inorganic acid substance, preferably having an ionization constant. of the order of 150 10 (25 C.) or

, greater. Added materials which have been found particularly suitable are hydrogen chloride, hy-\ 3 drogen bromide, and halo acetic acids, such as mono-, diand tri-chloraceticacids, and which do not enter into vigorous chemical reaction with theollto' cause sludging,'such as is the case with 1Dhuric acid.

nThQ jGXtI'aCtiOII solvents may comprise dichlorethyl "ether, ,nitrobenzene, phenol and halotphenols, such as ortho-chlorphenol, having a relatively high selectiveaction as between naphtheiiic; and paraflinic' constituents of the oil. Other selective solvents with which the invention may be advantageously employed comprise mixtures of sulphur dioxide and an auxiliary solvent,

o. S u'chfas benzoLand also mixtures, such as phenol or cresol,

Pro a e Jnffpracticing the inventionythe added mate- ,and a light. hydrocarbon, such as .1 trial. maybe mixed either with the oil undergoing I treatment, or with the extraction solvent prior to l'mlxing the extraction solvent with the oil. The extraction solvent, addedmaterial, and oil are subjected to mixing under conditions adapted to br ng abouteliicient contact therebetween, and ,then, permitted toseparate into extract and solvent liquid recovered therefrom. f litfhas been foundgthat the addition of a small This improvement is observed particularly in the case of heavy residual lubricating oil stocks. Heavy mixed base residuum, for example, is usually of distinctly black color and when such oil is extracted with dichlorethyl ether or phenol, in order to segregate therefrom ra-fiinate oil of high viscosity index, the resulting raffinate oil will still retain the black color of the original oil. However, when the same extraction is made in the presence of a small amount of hydrogen chloride or chloracetic acid, the color of the resulting rafiinate oil will be green, and in some instances may be of a relatively light shade of green. In addition, there is a very marked reduction in the carbon residue content of the refined oil.

.The process of our invention is, therefore, particularly adapted to solvent refining residual lubricating oil fractions, or to lubricating oils containing solid and semi-solid asphaltic constituents. While in the case of distillate oils which are substantially free from these asphaltic constituents, treatment with a selective solvent in the presence of the highly ionizable material does not result in any substantial improvement over treatment with the solvent alone, nevertheless in the case of heavy distillate fractions, which are contaminated with these solid and semi-solid asphaltic constituents, a very substantial improvement in the reduction of residual carbon content is realized by solvent refining in the presence of the added highly ionizable material. The amount of acidic material to be added will depend upon the nature of the material used, although in' general the addition of up to about by volume of the solvent is sufiicient. On the other hand, when using a highly ionized substance, such as hydrogen chloride gas, it is usually sulficient merely to saturate the solvent with the gas. In this case, the acid material will comprise less than 1% by volume of the solvent.

It is also contemplated that the acidified extraction solvent, or a mixture of extraction solvent and ionized material, maybe used in conjunction with a diluent solvent liquid, such as a light petroleum fraction of the character of propane, butane, pentane, etc. The diluent may cessive extractions at the temperature indicated and using one part of solvent to onepartof oil.

Rafiinate '(a) was obtained by extracting with a solvent composed of 75% phenol and 25% ortho-cresol,

Rafiinate (b) was obtained by extracting with a solvent composed of 75% phenol and 25% ortho-cresol saturated with hydrogen chloride,

Rafilnate (c) was obtained by extractingwith a solvent composed of 45% ortho-chlorphenol, 45%.phenol and 10 chloracetic acid.

Rcsidullm (a) (b) (c) Gravity, A. P. I 17. 8 22. 7 23. 1 24; 2 Saybolt Univ. vis.:

At F- i 4400 2300 1850 1600 At 210 F 159 112 j 101 Viscosity index 56 77 79 75 Percentcarbon ms. 6. 9 4. 8 3. 6 2. 4 Color Black Black Green Green Percent yield i... 100 6 56. 9 Extraction temp 781 78 F 78 F 72 F Comparing (a) and (b) above, it'will'be observed that the rafiinate oil obtained when using the acidified solvent was of improved color and slightly higher viscosity index than when using the solvent alone. A slightly higher yield of raffinate oil was also obtained. In addition, the use of the acidified solvent resulted in a reduction of the carbon residue content, namely, 3.6% as compared'with 4.8% when using the solvent alone.

In the-case of'raffinate (c), it will be observed that improved results were obtained when extracting with a mixture of 'ortho-chlorphenol and phenol inthe presence of 'chloracetic' acid, that is, the oil had a carbon residue content'of 2.4% and also was green in color.

The following examples afford a comparison of the results obtained "when extracting the same residual oilwithdichlorethyl ether alone, and with dichlorethyl ether in the presence of hydrogen chloride, and also inthe presence of trichloracetic acid. As in the previous case, the oil was subjectedto two successive extractions with the solvent at the temperaturesindicatedj. using one part of solvent to one part 'of' oil.

Dich'lorethyl 90%.dichlor- Dlchloretherssatw. ethyl ether ethyl rated with and 10% triether hydrogen chloracetic chloride acid 3400 2000 1683 154. 5 116. 5 107 75 78 81 5. 7 3. 5 2.8 Black Green Dark-green Percent .y eld 59. 0 55. 3 65. l Extraction temp 80F 80 F 72'F.

As indicated from the foregoing tabulatiomthe rafii'nate oilobtained by extracting the residuum with dichlorethyl ether saturated with hydrogen chloride was of lighter color and of somewhat higher viscosity index than that obtained by using the solvent alone; also, it had a much lower carbon residue content, namely, 3.5% as compared with 5.7% in the case of extracting with the solvent alone.. It will be observed that when using the solvent alone; the carbon residue content of the raffinate oil is only slightly lower than that of the original oil which was 6.9%.

The presence of the acid also has the further advantage of facilitating separation between extract andraffinatephases. When extracting the residuum with. dichlorethyl ether alone, the separation into. thev two phases was attended with considerable difficulty due to the formation of an emulsion. .On theother hand, it was found that when extracting with the acidified solvent, the presence of acid apparently inhibited the formation:of the'emulsion, or operated to facilitate its rapid breaking down, and thus greatlyfacilitatin'g separation into the two phases.

It will also be observed that'extracting.this residuum with chlorex in the presence of. 10% trichloracetic acid gave very satisfactory results. in that the carbon residue content-of the, raf-' finate oil was even lower than that obtained'when. extracting with the same solvent saturated with hydrogen chloride. Moreover, a higher yield'of higher viscosity index oil was also obtained;

Elimination of emulsion difficulties rendersthe invention particularly beneficial 'as applied to the so-called "Duo-sol refining operation wherein the. oil is extracted with a solvent, such as ore sol or cresylic acid, in the presenceof propane. This type of'operationis. carriedout in a.con-- tinuous'countercurrent tower systemand, there,- fore, reductionin the extent of emulsification is desirable from the standpoint of realizingrapid' dioxide, in .the absence of 'water, ,does not provide.

a highly ionizable substance, andlinactualsoL-l vent-refining operations there is no Water. pres: ent. Consequently, the addition. of the ionizable. substance of our invention givesimprovedresults. with solventmixtures containingsulphur dioxide.

The process of this invention is applicable. to the. treatment of lubricating, oil' stock, either before or after dewaxing. The treatment maybe. carried out in suitable batch or in continuous countercurrent fiow operation. 1

The proportions of solvent-,liquid, as. wellas the temperatures may; vary considerably from those described above in connection with .the specific examples, and the particular. conditions usedwilldepend to. alarge extent .uponethenar ture of. the oil. undergoing treatment as well as on the degree of separation desired.

Obviously, many modifications and. variations of. the invention, asehereinbefore set forth,.may be made withoutdeparting fromthe spirit and scope thereof, and therefore. only such. limitae tions should beimposed as are indicated in the appended. claims.

. We claim:

1. In the. manufacture .of. relatively lightcolored lubricatingoil of low residual. carboncontent from. a petroleum residue, the steps com.- prising extracting the residue with a solvent mix.- ture comprising about equal parts of orthochlore phenoland phenol, and containing up to. about 10% chloraceticacid by'volume of the solvent I mixture, forming an extract phase containing low'viscosity index constituents together with dark-colored and residual carbon-forming constituents dissolved in the solvent, and a rafilnate phase comprising relatively high viscosity index 011 substantially free from the undesired constit'uents, and separating the two phases.

2. In the manufacture of relatively lightcoloredlubricating oil of low residual carbon content from a petroleum residue, the steps com- 7 prising extracting the residue with a solvent mixture comprising orthochlorphencl and phenol in proportions such that the mixture exerts selective "action between low and high viscosity index constituents and containing up to'about 10% chloracetic acid by volume of the solvent mix- 7 ture, forming an extract phase containing low viscosity index constituents together with darkcolored and residual carbon-forming constituents dissolved in'the solvent, and a raflinate phase comprising relatively high viscosity index cil substantially free from the undesired constituents,

and separating the two phases.

3. Themethod according to claim 1 in which the residue undergoing treatment is diluted with a low-boiling petroleum hydrocarbon.

30' cred lubricating oilof low residual carbon con- L'tent from a petroleum residue, the steps comprising diluting the residue with a low-boiling 4.! The method according to claim 2 in which the residue undergoing treatment is diluted with alow-boiling petroleum hydrocarbon.

5. In the manufacture of relatively light-colpetroleum hydrocarbon, extracting the mixture with a solvent mixture comprising crthochlorphenol. and phenol in proportions such that the mixture exerts selective action between low and high viscosity index constituents and containing a small amount of acid having an ionization constant of the order of 150 X 10* and above, and which does not enter into vigorous chemical reaction with the oil such that the solvent mixture exerts a high degree of solvent action upon dark-colored and residual carbon-.forming constituents of the oil, forming an extract phase containing low viscosity index constituents together with dark-colored and residual carbonforming constituents dissolved in the solvent and a raffinate phase comprising relatively high viscosity index oil substantially free from the unphases.

'6. In the manufacture of relatively light-colcred lubricating oil of low residual carbon content from a'petroleum residue, the steps comprising extracting the residue with a solvent mixture comprising orthochlorphenol and phenol in proportions such that the mixture exerts selective action between low and high viscosity index constituents, and containing up to about of acid having an ionization constant of the order of 150 X 10* and above, and which does not enter into vigorous chemical reaction with the oil, forming an extract phase containing low viscosity index constituents together with darkcolored and residual carbon-forming constituents dissolved in the solvent, and a rafiinate phase I comprising relatively high viscosity index oil sub- 

